In a typical radio communications network, wireless terminals, also known as mobile stations and/or user equipments (UEs), communicate via a Radio Access Network (RAN) to one or more core networks. The RAN covers a geographical area which is divided into cell areas, with each cell area being served by a base station, e.g., a radio base station (RBS), which in some networks may also be called, for example, a “NodeB” or “eNodeB”. A cell is a geographical area where radio coverage is provided by the radio base station at a base station site or an antenna site in case the antenna and the radio base station are not collocated. Each cell is identified by an identity within the local radio area, which is broadcast in the cell. Another identity identifying the cell uniquely in the whole mobile network is also broadcasted in the cell. The base stations communicate over the air interface operating on radio frequencies with the user equipments within range of the base stations.
In some versions of the RAN, several base stations are typically connected, e.g., by landlines or microwave, to a controller node, such as a radio network controller (RNC) or a base station controller (BSC), which supervises and coordinates various activities of the plural base stations connected thereto. The RNCs are typically connected to one or more core networks.
A Universal Mobile Telecommunications System (UMTS) is a third generation mobile communication system, which evolved from the second generation (2G) Global System for Mobile Communications (GSM). The UMTS Terrestrial Radio Access Network (UTRAN) is essentially a RAN using Wideband Code Division Multiple Access (WCDMA) and/or High Speed Packet Access (HSPA) for user equipments. In a forum known as the Third Generation Partnership Project (3GPP), telecommunications suppliers propose and agree upon standards for e.g. third generation networks and further generations, and investigate enhanced data rate and radio capacity.
Specifications for the Evolved Packet System (EPS) have been completed within the 3GPP and this work continues in the coming 3GPP releases. The EPS comprises the Evolved Universal Terrestrial Radio Access Network (E-UTRAN), also known as the Long Term Evolution (LTE) radio access, and the Evolved Packet Core (EPC), also known as System Architecture Evolution (SAE) core network. E-UTRAN/LTE is a variant of a 3GPP radio access technology wherein the radio base stations are directly connected to the EPC core network rather than to RNCs. In general, in E-UTRAN/LTE the functions of a RNC are distributed between the radio base stations, e.g., eNodeBs in LTE, and the core network. As such, the RAN of an EPS has an essentially “flat” architecture comprising radio base stations without reporting to RNCs.
Packets are transported in a Core Network along paths in a transport network also referred to as a communications network herein. Today two broad category of transport networking is available. In one, called automatic, path selection is automatic, usually distributed, and, usually, follows the shortest path paradigm. Internet Protocol (IP) routing, IP/Multiprotocol label switching (MPLS), and Ethernet Shortest Path Bridging (SPB) clearly fall into this category. The other approach, called traffic engineering, is more circuit aware and relies on setting up explicit paths across the network with usually resource reservation included. Generalized MPLS (GMPLS), MPLS-Transport Profile (TP), Provider Backbone Bridges Transport Profile (PBB-TP) and Resource Reservation Protocol (RSVP) all fall into this category.
Automatic solutions are great and have low management burden. By most of the time relying on shortest paths they also achieve some form of low delay efficiency. They can be expanded with automatic fast reroute and Equal-Cost Multipath (ECMP) to increase reliability and network utilization. The automatic solutions, however, fail to offer Quality of Service (QoS) measures. Usually simple packet priorities or DiffServ handling accompanies them with no effort to guarantee any sort of bandwidth even in a soft way.
Traffic engineering solutions are focusing on reserving capacity to flows and are more suited to provide bandwidth guarantees, but path computation may be potentially very complicated if alternative paths want to be used for higher utilization. Also, robustness is usually achieved by reserving an alternative path, which is a waste of resources. Transport equipment, such as communication nodes, usually has very limited packet processing capabilities. A few priority or weighted fair queues, a few levels of drop precedence is what are usually available, since emphasis is on high throughput and low price per bit.